Spinous process fixation system and methods thereof

ABSTRACT

An implantable device includes a barrel. The barrel has a first portion and a second portion. The implantable device includes a first plate having multiple projections extending from one side of the first plate, where the first plate is configured to movably couple to the first portion of the barrel. The implantable device includes a second plate having multiple projections extending from one side of the second plate, where the second plate is configured to movably couple to the second portion of the barrel. The barrel is configured to transition from a collapsed form having a first height to an expanded form having a second height, where the second height is greater than the first height.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patent application Ser. No. 14/629,705 filed on Feb. 24, 2015, which is a continuation application of U.S. patent application Ser. No. 13/731,504, filed Dec. 31, 2012, which is entitled “Spinous Process Fixation System and Methods Thereof.” The entire application is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

This description relates to medical devices and systems and more particularly to a spinous process fixation system and methods thereof. In particular, in one or more implementations, this description relates to spinous process fusion devices that distract and/or immobilize the spinous processes of adjacent vertebrae.

BACKGROUND

A variety of medical devices and medical device systems may be implanted within a body of a patient to provide support to a portion or portions of the patient's body. For example, some medical devices may be implanted and coupled to backbones or portions of a spine of a patient and may be configured to provide support to the spinal bone structure of the patient.

Typically, weaknesses in the spine are corrected using devices that fuse one or more vertebrae together. It may be desirable to have an implantable device that provides for structural stability to adjacent vertebrae and to achieve supplemental fusion to treat weaknesses in the spine due to degenerative disc disease, spondylolisthesis, trauma (i.e., fracture or dislocation), tumor and/or other causes.

SUMMARY

According to one general aspect, an implantable device includes a barrel. The barrel has a first portion and a second portion. The implantable device includes a first plate having multiple projections extending from one side of the first plate, where the first plate is configured to movably couple to the first portion of the barrel. The implantable device includes a second plate having multiple projections extending from one side of the second plate, where the second plate is configured to movably couple to the second portion of the barrel. The barrel is configured to transition from a collapsed form having a first height to an expanded form having a second height, where the second height is greater than the first height.

Implementations may include one or more of the following features. For example, the barrel may include a frame, a first endplate having a curved shape and a second endplate having a curved shape. The first endplate and the second endplate may be coupled to the frame to form the barrel, where the barrel has a bulleted shape in both a lateral direction and a posterior direction. The barrel may include a frame, a first endplate, a second endplate, a first actuator having a split ramp inserted into the frame, a second actuator having a split ramp inserted into the frame and a central screw inserted through the first actuator and the second actuator, where the first actuator and the second actuator are configured to act on the first endplate and the second endplate in response to a rotation of the central screw. The barrel may include a first window and a second window, where the first window and the second window may be configured to receive graft packing material. The barrel may include a first endplate having a shaped groove and a second endplate having a shaped groove.

For example, in one implementation, the first portion and the second portion may be rails that extend from a same side of the barrel. For example, in another implementation, the first portion and the second portion may be rails that each extend from a different side of the barrel.

For example, the first plate and the second plate are each shaped in a lordotic profile. The first plate may include a bushing to enable the first plate to angulate about the bushing and the second plate may include a bushing to enable the second plate to angulate about the bushing. The first plate may be locked in position using a first set screw at any position within a range of motion for the first plate and the second plate may be locked in position using a second set screw at any position within a range of motion for the second plate. The first set screw may include a cup-shaped end to lock the first plate in position and the second set screw may include a cup-shaped end to lock the second plate in position.

In another general aspect, an implantable device includes a barrel having a first portion and a second portion, a first plate having multiple projections extending from one side of the first plate, where the first plate is configured to movably couple to the first portion of the barrel and to angulate about an axis of the first portion, and a second plate having multiple projections extending from one side of the second plate, where the second plate is configured to movably couple to the second portion of the barrel and to angulate about an axis of the second portion. The first plate and the second plate are each shaped in a lordotic profile.

Implementations may include one or more of the following features. For example, the first plate may be configured to angulate up to about 25 degrees about the axis of the first portion and the second plate may be configured to angulate up to about 25 degrees about the axis of the second portion. In one implementation, the first portion and the second portion may be rails that extend from a same side of the barrel. In another implementation, the first portion and the second portion may be rails that each extend from a different side of the barrel.

For example, the barrel may be configured to transition from a collapsed form having a first height to an expanded form having a second height, where the second height is greater than the first height. The first plate may be locked in position using a first set screw at any position within a range of motion for the first plate, where the first set screw has a cup-shaped end, and the second plate may be locked in position using a second set screw at any position within a range of motion for the second plate, where the second set screw has a cup-shaped end.

In another general aspect, a method includes inserting a barrel of an implantable device into an interspinous space. The implantable medical device includes the barrel having a first portion and a second portion, a first plate having multiple projections extending from one side of the first plate and a second plate having multiple projections extending from one side of the second plate. The method includes expanding the barrel from a collapsed form having a first height to an expanded form having a second height, where the second height is greater than the first height, moving the first plate on the first portion to engage a spinous process and moving the second plate on the second portion to engage the spinous process.

Implementations may include one or more of the following features. For example, the method may include engaging set screws in the first plate and the second plate to lock the first plate and the second plate in position. The method may include positioning the first plate to a desired angle with respect to the first portion, positioning the second plate to a desired angle with respect to the second portion and engaging set screws in the first plate and the second plate to lock the first plate and the second plate in position.

The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a medical device according to an example implementation.

FIG. 2 is a top view of the medical device of FIG. 1.

FIG. 3 is a front view of the medical device of FIG. 1.

FIG. 4 is a side view of the medical device of FIG. 1.

FIG. 5 is a perspective view of a medical device according to an example implementation.

FIG. 6 is a top view of the medical device of FIG. 5.

FIG. 7 is a front view of the medical device of FIG. 5.

FIG. 8 is a side view of the medical device of FIG. 5.

FIG. 9 is a perspective view of a medical device according to an example implementation.

FIG. 10 is a top view of the medical device of FIG. 9.

FIG. 11 is a front view of the medical device of FIG. 9.

FIG. 12 is a side view of the medical device of FIG. 9.

FIG. 13 is a perspective view of a medical device according to an example implementation.

FIG. 14 is a top view of the medical device of FIG. 13.

FIG. 15 is a front view of the medical device of FIG. 13.

FIG. 16 is a side view of the medical device of FIG. 13.

FIG. 17 is a perspective view of a medical device according to an example implementation.

FIG. 18 is a top view of the medical device of FIG. 17.

FIG. 19 is a front view of the medical device of FIG. 17.

FIG. 20 is a side view of the medical device of FIG. 17.

FIG. 21 is a top view of a medical device according to an example implementation.

FIG. 22 is a side view of the medical device of FIG. 21.

FIG. 23 is a detailed view of the inset A of FIG. 22.

FIGS. 24-27 are side views of a plate of a medical device according to an example implementation.

FIG. 28 is top view of a barrel of a medical device according to an example implementation.

FIG. 29 is an exploded front view of a barrel of a medical device according to an example implementation.

FIG. 30 is an exploded top view of a barrel of a medical device according to an example implementation.

FIG. 31 is a perspective view of a medical device according to an example implementation.

FIG. 32 is a top view of the medical device of FIG. 31.

FIG. 33 is a front view of the medical device of FIG. 31.

FIG. 34 is a side view of the medical device of FIG. 31.

FIG. 35 is a perspective view of a medical device according to an example implementation.

FIG. 36 is a top view of the medical device of FIG. 35.

FIG. 37 is a front view of the medical device of FIG. 35.

FIG. 38 is a side view of the medical device of FIG. 35.

FIG. 39 is a perspective view of a medical device according to an example implementation.

FIG. 40 is a top view of the medical device of FIG. 39.

FIG. 41 is a front view of the medical device of FIG. 39.

FIG. 42 is a side view of the medical device of FIG. 39.

FIG. 43 is a perspective view of a medical device according to an example implementation.

FIG. 44 is a top view of the medical device of FIG. 43.

FIG. 45 is a front view of the medical device of FIG. 43.

FIG. 46 is a side view of the medical device of FIG. 43.

FIG. 47 is an exploded top view of a barrel of a medical device according to an example implementation.

FIG. 48 is a flow chart illustrating an exemplary method including the medical device of FIG. 1.

DETAILED DESCRIPTION

Detailed implementations of the present invention are disclosed herein; however, it is to be understood that the disclosed implementations are merely examples of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting, but rather to provide an understandable description of the invention.

The terms “a” or “an,” as used herein, are defined as one or more than one. The term “another,” as used herein, is defined as at least a second or more. The terms “including” and/or “having”, as used herein, are defined as comprising (i.e., open transition).

The devices and methods described herein are generally directed to medical devices that can be used to support, stabilize and/or replace anatomical structures within a body of a patient. In some implementations, the devices and methods described herein are configured to provide support to a spine or back of a patient, including providing support between two vertebrae in the spine or back of the patient. In other implementations, other portions of the body of the patient can be supported by the devices described herein.

The medical devices described herein may be implanted within a body of a patient to assist in maintaining normal physiologic motion in the spine of the patient.

The term patient may be used hereafter for a person who benefits from the medical device or the methods disclosed in the present invention. For example, the patient may be a person whose body receives the medical device disclosed by the present invention in a surgical treatment. For example, in some embodiments, the patient may be a human female, human male, or any other mammal.

This document describes implementations of an implantable medical device that may be used as a posterior, non-pedicle supplemental fixation device for use in the non-cervical spine. The medical device may be used as an interspinous fusion device. The medical device may be implanted with or without the removal of the supraspinous ligament. In one or more implementations, the supraspinous ligament may be preserved. The medical device may be attached firmly to the spinous processes above and below an interspinous space. The medical device may immobilize a lumbar motion segment posteriorly with no other devices implanted. The medical device may withstand compressive, torsional and shear loads seen in the lumbar spine. The medical device may be used to achieve supplemental fusion and to treat conditions of the spine such as, for example, degenerative disc disease, spondylolisthesis, trauma (i.e., fracture or dislocation), tumor and/or other conditions.

This document describes implementations of an implantable medical device, where the medical device may include an expandable central barrel with polyetheretheketone (PEEK) bone contacting endplates, with two spiked plates held together on posterior rails. The plates include projections (e.g., spikes) that bite into the spinous process to clamp the device in place. Each of the plates may angulate to conform to the patient anatomy. The plates may be locked with a set screw and may have a lordotic profile to match the lumbar anatomy. The expandable barrel may provide interspinous distraction, off-loading the spikes on the plate and reducing the chances of breaking the spinous process. The barrel may be sized to fit into the interspinous space without resistance, and then expanded. The barrel may include a graft window anteriorly and posteriorly and may be packed with graft material after expansion using the posterior window. The PEEK endplates may include anatomically-shaped grooves for optimal bone contact and fit.

FIGS. 1-4 illustrate a medical device 10 according to one example implementation. The medical device 10 may be implanted in a patient and referred to as a spinous process fusion device. FIG. 1 is a perspective view of the medical device 10 with a barrel illustrated in a collapsed or contracted position and the plates in a separated position relative to one another. FIGS. 2-4 illustrate a top view, front view and side view, respectively, of the medical device 10 of FIG. 1, which illustrates the barrel in the collapsed or contracted position.

The medical device 10 includes a first plate 12, a second plate 14 and an expandable central barrel (also referred to as a barrel) 16. The barrel 16 is illustrated in a collapsed state. The barrel 16 includes a first portion 18 (e.g., a first rail 18) and a second portion 20 (e.g., a second rail 20) The first rail 18 and the second rail 20 also may be referred to as the rails 18 and 20. The first rail 18 and the second rail 20 may be integrally formed with the barrel 16. The first rail 18 and the second rail 20 also may be referred to as posterior rails. The first plate 12 and the second plate 14 (also referred to as the plates 12 and 14) may be secured to the barrel 16 by coupling the first plate 12 to the first rail 18 and the second plate 14 to the second rail 20. The first plate 12 and the second plate 14 each may include a bushing 22 (e.g., a spherical bushing) assembled into the plates 12 and 14, where the plates 12 and 14 slide on the respective rails 18 and 20 through the bushing 22 and are secured using a set screw 24. As discussed in more detail below, each plate 12 and 14 may move laterally along its respective rail 18 and 20 to engage spinous processes of adjacent vertebra above and below the interspinous space. FIGS. 1-4 illustrate the plates 12 and 14 in a separated position with respect to one another. Also, as discussed in more detail below, each plate 12 and 14 may angulate through a range of degrees with respect to the rails 18 and 20 to better conform to patient anatomy when implanted in a patient.

In other example implementations (not shown), the first portion 18 and the second portion 20 may be grooves on the barrel 16. In this example, the first plate 12 and the second plate 14 each may include a projection (e.g., a rail) that is movably inserted into the corresponding groove on the barrel 16. This example implementation may function in the same way as described above and below, other than the structure of the rails may be implemented on the plates 12 and 14, which are then received in the first portion 18 and the second portion 20 of the barrel 16, where the first portion 18 and the second portion 20 are grooves on the barrel 16.

The first plate 12 may include an upper portion 26 and a lower portion 28. The second plate 14 may include an upper portion 30 and a lower portion 32. The plates 12 and 14 may include multiple projections 34 (e.g., spikes) on both the upper portions 26 and 30 and the lower portions 28 and 32. While the term spikes may be used for the projections 34 other types of projections may be used that may have a more tapered point or rounded point or other type of ending to the projection. The spikes 34 may be used to attach firmly and bite into the spinous processes above and below an interspinous space. The spikes 34 may be integrally formed with the plates 12 and 14 or the spikes 34 may be separate components that are secured to the plates 12 and 14. The spikes 34 may be pyramid shaped with a base portion secured or integrally formed on the plates 12 and 14. The sides of the spikes 34 may extend from the base to form a point in the shape of a pyramid. In other example implementations, the spikes 34 may be formed into other shapes that raise to a point to enable the spike to engage the spinous process. As discussed above, the end of the spikes 34 may include tips other than a point such as, for example, rounded tip, a square tip or other-shaped tip.

The plates 12 and 14 and the spikes 34 may be made of titanium. In other implementations, the plates 12 and 14 and the spikes 34 may be made of other biocompatible materials.

The example illustration of the medical device 10 includes four (4) spikes 34 on each portion 26, 28, 30 and 32 of the plates 12 and 14. In other example implementations, fewer or more spikes 34 may be included. In one example implementation, the spikes 34 on opposing portions (i.e., upper portions 26 and 30 and lower portions 28 and 32) may be aligned across from one another. In other example implementations, the spikes 34 on opposing portions may be offset from one another.

The first plate 12 and the second plate 14 may be shaped in a lordotic profile to match the lumbar anatomy. With respect to the first plate 12, the upper portion 26 is connected to the lower portion 28 by a central portion 36. The upper portion 26, the lower portion 28 and the central portion 36 may be integrally formed as a single plate component. The central portion 36 includes an open side (e.g., a C-shaped opening) to receive the bushing 22 and an opening (e.g., a hole) to receive the set screw 24, as illustrated in more detail in FIGS. 24-27. In other example implementations, the first plate 12 and the second plate 14 may be other shapes suitable for a particular application.

Similarly to the first plate 12, the second plate 14 includes a central portion 38 that connects the upper portion 30 to the lower portion 32. The upper portion 30, the lower portion 32 and the central portion 38 may be integrally formed as a single plate component. The central portion 38 include an open side (e.g., a C-shaped opening) to receive the bushing 22 and an opening (e.g., a hole) to receive the set screw 24, as illustrated in more detail in FIGS. 24-27. The set screw 24 is used to lock the plates 12 and 14 in an angular position at any position within their range of angular motion.

The central barrel 16 is an expandable barrel that may be in a collapsed position for insertion into a patient in the interspinous space without resistance and then expanded up to the barrel's maximum height. In one example implementation, the maximum expanded height of the barrel may be about 4 mm greater than the collapsed height.

The central barrel 16 includes a first endplate 40 and a second endplate 42 (also referred to as endplates 40 and 42), as best viewed in FIG. 3. Each of the endplates 40 and 42 includes a respective groove 44 and 46. The grooves 44 and 46 may be anatomically-shaped grooves optimal bone contact and fit in the patient. The endplates 40 and 42 may be PEEK bone contacting endplates. The barrel 16 may be bullet-shaped on both ends in the lateral and posterior directions to facilitate insertion into a patient. The expandable barrel 16 may provide interspinous distraction and may offload the forces of the spikes 34 on the plates 12 and 14 to reduce the chances of breaking a spinous process. The barrel 16 may be inserted, laterally or posteriorly, in a smaller height and then expanded to provide distraction, eliminating forces on the spinous process and potential frustration for a surgeon performing the implantation.

The barrel 16 includes a first window 48 (e.g., also referred to as an opening or an anterior window) and a second window 50 (e.g., also referred to as an opening or a posterior window). The first window 48 and the second window 50 may be used as graft windows for the packing of bone graft material following the insertion and placement of the medical device 10 in a patient. In one implementation, after the barrel 16 has been expanded, the barrel 16 may be packed with bone graft using the second window 50. In this manner, graft containment areas accessed by the windows 48 and 50 may provide for a larger grafting area and may be packed after expansion of the barrel 16.

Referring to FIGS. 5-8, an example implementation of the medical device 10 of FIGS. 1-4 is illustrated with the barrel 16 shown in an expanded state and the plates 12 and 14 shown in a separated position with respect to one another. That is, the plates 12 and 14 are each positioned towards an outer end of the rails 18 and 20. The barrel 16 expands and contracts by expanding and contracting the endplates 40 and 42 in a direction towards the upper 26 and 30 and lower portions 28 and 32 of the sides 12 and 14, respectively. The mechanism to expand and contract the barrel 16 is illustrated in more detail in FIGS. 28-30 below.

In general, a central screw 52 is rotated to actuate two independent internal actuators. The actuators include split ramps that raise and lower the endplates 40 and 42 when the central screw 52 is rotated. FIGS. 7 and 8 provide views that illustrates the barrel 16 in a fully expanded state. As discussed above, the barrel 16 may be expanded after insertion into the interspinous space. After expansion, the barrel 16 may be packed with bone graft material using the window 50. Prior to expansion, some bone graft material may be packed into the barrel 16 using the window 48.

Referring to FIGS. 9-12, an example implementation of the medical device 10 of FIGS. 1-4 is illustrated with the barrel 16 shown in a collapsed state and the plates 12 and 14 shown in a closed position. That is, the plates 12 and 14 have been traversed along the rails 18 and 20 towards one another. The plates 12 and 14 may slide along the rails 18 and 20 and may be secured in position at any point along the rails 18 and 20 using the set screw 24. When the plates 12 and 14 are slid together along the rails 18 and 20, the spikes 34 on the plates 12 and 14 may engage and clamp (or bite into) the spinous process. In this manner, the spikes 34 on the upper portions 26 and 30 may clamp together and into one spinous process and the spikes 34 on the lower portions 28 and 32 may clamp together and into an adjacent spinout process.

As illustrated in FIGS. 9-12, the spikes 34 on one plate are aligned to mate at a same point with the spikes 34 on an opposing plate. In other example implementations, the spikes 34 on one plate may be offset in relation to the spikes 34 on an opposing plate.

Referring to FIGS. 13-16, an example implementation of the medical device 10 of FIGS. 1-4 is illustrated with the barrel 16 shown in an expanded state and the plates 12 and 14 shown in a closed position. In this manner, this illustrates the medical device 10 in a state after insertion into the patient such that the plates 12 and 14 have been traversed along the rails 18 and 20 to clamp on the spinous process of adjacent vertebrae and the barrel 16 has been expanded using the central screw 52.

Referring to FIGS. 17-23, an example implementation of the medical device 10 of FIGS. 1-4 is illustrated with the barrel 16 shown in an expanded state and the plates 12 and 14 shown in an open or separated position and in an angulated configuration. As discussed above, the plates 12 and 14 may rotate angularly with respect to the rails 18 and 20. The plates 12 and 14 may pivot around the bushing 22 and may be locked in place using the set screw 24. In one example implementation, the plates 12 and 14 may have a range of motion of about 25 degrees offset with respect to the rails 18 and 20. The angulation of the plates 12 and 14 enables each plate to conform independently to the anatomy of the particular patient. Each plate 12 and 14 may be pivoted and locked at any position in their range of motion independent of the other plate.

In FIGS. 22 and 23, a side view (FIG. 22) and a detailed view of inset A (FIG. 23) illustrate that the plates 12 and 14 are locked using the set screw 24. The rails 18 and 20 may be C-shaped or curved and include a groove area 60. The set screw 24 may include a curved, cup-shaped design on the tip 62. The curved tip 62 penetrates through the opening in the rail 14 and through the bushing 22 to engage the groove area 62 of the rail 20 to secure and lock the plate 14 in place. The curved tip 62 maximizes the surface contact with the groove area 62 of the rail 20 when the plate 14 pivots through its range of motion. FIGS. 24-27 below also illustrate the curved (or cup-shaped or bulleted) tip 62 of the set screw 24.

Referring to FIGS. 24-27, the assembly of the plates 12 and 14 is illustrated. In these example figures, plate 14 is referenced for illustrative purposes. The plate 14 may be assembled by placing the bushing 22 into the plate initially offset by 90 degrees from its final position. As described above, the bushing 22 may be a spherical bushing that is shaped to be positioned on and traverse the rail 20 on the barrel 16. The bushing 22 may include a slot 64 or opening in the back of the bushing to receive the set screw 24.

Once the bushing 22 has been inserted into the plate 14 (FIG. 25), the bushing 22 is rotated 90 degrees into its final position in the plate 14 (FIG. 26). Then, the set screw 24 having the curved tip 62 may be inserted through the opening in the back of the plate 14 through the slot 64 in the bushing 22. The set screw 24 serves to prevent the bushing 22 from rotating back out of the plate 14.

Referring to FIGS. 28-30, the barrel 16 and assembly of the barrel 16 is illustrated in detail. As discussed above, the barrel 16 includes a first endplate 40 and a second endplate 42. The endplates 40 and 42 may be PEEK endplates. The barrel 16 includes a central screw 52 having a first thread portion 66 and a second thread portion 68. The barrel 16 includes a frame 65, a first actuator 70 and a second actuator 72 (also referred to as the actuators 70 and 72) and two assembly pins (not shown). In one example implementation, the frame 65, the actuators 70 and 72 and the central screw 52 may be made of titanium. In other example implementations, the components may be made of other biocompatible materials.

Each of the actuators 70 and 72 may include split ramps 74 and 76 to accommodate the curved shape of the barrel 16. The barrel 16 is curved shaped and may be bulleted (or egg-shaped) on each end to allow for easier insertion into the interspinous space. The curved shape of the barrel 16 may provide maximum graft packing volume.

The actuators 70 and 72 may be loosely assembled into the frame 65 of the barrel 16 and the 74 and 76 placed over the actuators 70 and 72. The central screw 52 may be inserted into the actuators 70 and 72 and timed so that the actuators have specific spacing per rotation of the screw 52. Once the screw 52 is fully inserted, two pins (not shown) are pressed into the frame 65 posteriorly to capture the screw 52 to prevent its disassembly.

The rotation of the screw 52 causes the actuators 70 and 72 to rotate and the ramps 74 and 76 on the actuators 70 and 72 to push against the endplates 40 and 42, causing the endplates 40 and 42 to expand from a collapsed position. A counter rotation of the screw 52 causes the actuators 70 and 72 to rotate and the ramps 74 and 76 on the actuators 70 and 72 to recede from pushing against the endplates 40 and 42, causing the endplates 40 and 42 to collapses from an expanded state.

FIGS. 31-34 illustrate a medical device 100 according to an example implementation. Similarly to the medical device 10, the medical device 100 may be implanted in a patient and referred to as a spinous process fusion device. Like reference numbers between the FIGS. 1-30 and FIGS. 31-34, and other figures below describing medical device 100, refer to the same or similar components and features between the two medical devices. The medical device 100 may have the same features and functionality as the medical device 10.

The medical device 100 includes a first plate 12 and a second plate 14. The medical device 100 includes a barrel 116. In the example of FIGS. 31-34, the barrel 116 includes rails 118 and 120 that each extend from a different side of the barrel 116 instead of extending from a same side like the rails 18 and 20 from the barrel 16 in medical device 10. The barrel 116 is essentially rotated 90 degrees compared to the barrel 16. In other aspects, the barrel 116 is an expandable barrel and has the same functionality as the barrel 16. The barrel 116 may be inserted laterally into a patient in the interspinous space. The barrel 116 may be inserted at a smaller height (or in a collapsed state) and then expanded to provide distraction and to eliminate the forces on the spinous process and frustration for the surgeon.

In FIGS. 31-34, the medical device 100 illustrates the plates 12 and 14 in an open state and the barrel 116 in a collapsed state. In this manner, the medical device 100 may inserted into a patient and then the barrel 116 expanded.

Referring to FIGS. 35-38, the medical device 100 is illustrated with the barrel 116 in an expanded state. In one example implementation, the expanded barrel height for the barrel 116 may be about 7 mm greater than the collapsed height. The sides 12 and 14 are illustrated in an open state. The barrel 116 may be expanded from a collapsed state to an expanded state using the central screw 152. Similarly, the barrel 116 may be collapsed from an expanded state to a collapsed state using the central screw 152.

Referring to FIGS. 39-42, the medical device 100 is illustrated with the barrel 116 in an expanded state and the plates 12 and 14 in a closed position. As discussed above with respect to the medical device 10, the plates 12 and 14 on the medical device 100 also may traverse the rails 118 and 120 of the barrel between an open position and a closed position. In the closed position, the plates 12 and 14 are designed to clamp and bite into the spinous process, as discussed above in detail.

Referring to FIGS. 43-46, the medical device 100 is illustrated with the barrel 116 in an expanded state and the plates 12 and 14 in a closed and angulated position. As discussed above with respect to FIGS. 17-20, the plates 12 and 14 may angulate about 25 degrees with respect to the rails 118 and 120 to better conform to patient anatomy. The plates 12 and 14 may be locked in position using the set screw 24.

Referring to FIG. 47, the barrel 116 is assembled in a manner similar to the barrel 16, as discussed above with respect to FIGS. 28-30. The barrel 116 includes a first endplate 140 and a second endplate 142, two independent actuators with ramps and a central screw 152. The endplates 140 and 142 are loosely assembled into the actuator ramps and the central screw 152 is inserted into the actuator ramps, which anchor the assembly together.

Referring to FIG. 48, an example flowchart illustrates an example process 200 for using the medical devices 10 and 100. For example, process 200 includes inserting a barrel 16 or 116 of the medical device 10 or 100, respectively, into an interspinous space (210). As discussed above, the medical device includes the barrel 16 or 116 having a first portion (e.g., rail 18 or 118) and a second portion (e.g., rail 20 or 120), a first plate 12 having multiple projections 34 extending from one side of the first plate 12 and a second plate 14 having multiple projections 34 extending from one side of the second plate (210).

The process 200 includes expanding the barrel 16 or 116 from a collapsed form having a first height to an expanded form having a second height, where the second height is greater than the first height (220). As discussed above, the central screw 52 or 152 may be rotated to expand the barrel 16 or 116 from a collapsed form to an expanded form in the interspinous space.

The process includes moving the first plate 12 on the first portion (e.g., rail 18 or 118) to engage a spinous process (230) and moving the second plate 14 on the second portion (e.g., rail 20 or 120) to engage the spinous process (240). For example, the projections 34 on each of the plates 12 and 14 may engage the spinous process of adjacent vertebrae as the plates 12 and 14 are slid along the respective rails.

Optionally, the process 200 may include positioning the first plate 12 to a desired angle with respect to the first portion and positioning the second plate 14 to a desired angle with respect to the second portion. Once the plates 12 and 14 have been positioned to their desired angles, the plates 12 and 14 may be locked into position using the set screws 24.

The various components of the medical device 10 and the medical device 100 described herein can be formed with any biocompatible material used for such a medical device. For example, each of the various components can be formed with one or more biocompatible plastics and/or one or more biocompatible metals such as, for example, titanium and stainless steel.

While certain features of the described implementations have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the scope of the embodiments. It should be understood that they have been presented by way of example only, not limitation, and various changes in form and details may be made. Any portion of the apparatus and/or methods described herein may be combined in any combination, except mutually exclusive combinations. The embodiments described herein can include various combinations and/or sub-combinations of the functions, components and/or features of the different embodiments described. 

What is claimed is:
 1. An implantable device for engaging spinous processes comprising: a barrel having a longitudinal axis; a first plate having multiple projections adapted to engage at least one spinous process, the first plate configured to movably couple to the barrel; and a second plate having multiple projections adapted to engage the at least one spinous process, the second plate configured to movably couple to the barrel, wherein the barrel is configured to transition from a collapsed form having a first height to an expanded form having a second height, wherein the barrel comprises a first endplate, a second endplate, an actuator positioned between the first endplate and the second endplate, wherein the actuator includes a first ramp and a second ramp for abutting one of either the first end plate or the second endplate such that driving of the actuator along the longitudinal axis causes the first end plate to move vertically relative to the second end plate to cause expansion of the barrel, wherein the first and second plates are adapted to move independently of each other, and wherein the first plate comprises a bushing to enable the first plate to angulate about the bushing and the second plate comprises a bushing to enable the second plate to angulate about the bushing.
 2. The implantable device of claim 1, wherein the second height is greater than the first height.
 3. The implantable device of claim 1, wherein the barrel has a bulleted shape in both a lateral direction and a posterior direction.
 4. The implantable device of claim 1, further comprising a central screw threadably coupled to the actuator and adapted to move the first end plate relative to the second endplate to cause expansion of the barrel upon rotation of the central screw.
 5. The implantable device of claim 4, wherein the barrel further comprises a central screw inserted through the first ramp and the second ramp.
 6. The implantable device of claim 5, wherein the first ramp and the second ramp are configured to act on the first endplate and the second endplate in response to a rotation of the central screw.
 7. The implantable device of claim 1, wherein the barrel comprises a first window and a second window, the first window and the second window configured to receive graft packing material.
 8. The implantable device of claim 1, wherein the first endplate having a shaped groove and the second endplate having a shaped groove.
 9. The implantable device of claim 1, wherein the first plate and the second plate are each shaped in a lordotic profile.
 10. The implantable device of claim 1, wherein the first plate is locked in position using a first set screw at any position within a range of motion for the first plate and the second plate is locked in position using a second set screw at any position within a range of motion for the second plate.
 11. The implantable device of claim 10, wherein the first set screw includes a cup_shaped end to lock the first plate in position and the second set screw includes a cup_shaped end to lock the second plate in position.
 12. An implantable device for engaging spinous processes comprising: a barrel having a first portion and a second portion and having a longitudinal axis; a first plate shaped in a lordotic profile movably coupled to the barrel and adapted to engage at least one spinous process, wherein the first plate is capable of angulating relative to the first portion of the barrel; and a second plate shaped in a lordotic profile movably coupled to the barrel_and adapted to engage the at least one spinous process, wherein the second plate is capable of angulating relative to the second portion of the barrel, wherein the barrel is configured to transition from a collapsed form having a first height to an expanded form having a second height, wherein the barrel comprises a first endplate, a second endplate, an actuator positioned between the first endplate and the second endplate, wherein the actuator includes a first ramp and a second ramp for abutting one of either the first endplate or the second endplate such that driving of the actuator along the longitudinal axis causes the first end plate to move vertically relative to the second end plate to cause expansion of the barrel, wherein the first and second plates are adapted to move independently of each other.
 13. The implantable device of claim 12, wherein the first plate is configured to angulate up to about 25 degrees relative to the first portion and the second plate is configured to angulate up to about 25 degrees relative to the second portion.
 14. The implantable device of claim 12, wherein the first portion and the second portion are rails that extend from a same side of the barrel.
 15. The implantable device of claim 12, wherein the second height is greater than the first height.
 16. The implantable device of claim 12, wherein the first plate is locked in position using a first set screw at any position within a range of motion for the first plate, the first set screw having a cup-shaped end; and the second plate is locked in position using a second set screw at any position within a range of motion for the second plate, the second set screw having a cup-shaped end.
 17. The implantable of claim 12, further comprising a central screw threadably coupled to the actuator and adapted to move the first end plate relative to the second endplate to cause expansion of the barrel upon rotation of the central screw. 